Signaling system and method



1,530,482 G. c. CUMMINGS SIGNALING SYSTEM AND METHOD March 24, 1925.

Filed March 15, 1922 gJlEsrhom //7ve/1/on' George C Cu m/hys.

Patented Mar. 24, 1925.

UNITED STATES PATENT OFFICE.

GEO'BGE C. CUMMINGS, OF ORANGE, NFAV JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SIGNALING SYSTEM AND METHOD.

Application filed March 15, 1922. Serial No. 543,850.

To all whom it'may concern:

Be it known that I, GEORGE C. CUMuINcs, a subject of the King of England, residing at Orange, in the county of. Essex, State of New Jersey, have invented certain new and useful Improvements in Signaling Systems and Methods, of'which the following is a full, clear, concise, and exact description.

This invention relates to signaling systems and methods, and particularly to arrangements for operating composite telephone and telegraph systems.

In operating a telegraph system in conjunction with a telephone system operative over a metallic line, an interfering current may sometimes be induced in the paralleling conductors upon the operation of the transmitting equipment of the telegraph 'set. The interfering current may be produced, for eX- ample, by the connection of the composite equipment to said conductors. Such interfering currents cause a disturbance in the terminal apparatus which is frequently detrimental to the satisfactory and eflicient operation of the system and often times produce false operation of the receiving apparatus of the telegraph system.

It is an objectlof the present invention to impress a neutralizing current on the paralleling circuit, substantially of the same current amplitude, phase relation, and wave shape, in such a manner that the detrimental effects of the impulses induced therein through the composite equipment are overcome.

Referring to the drawings:

Fig. 1 shows schematically a circuit embodying one form of the invention;

Fig. 2 shows a modification of the invention as applied to a duplex system.

In Fig. 1 of the drawing, 4 and 5 represent two line conductors which have associated therewith both telegraph and tele* phone equipment thereby permitting simultaneous telegraphic and telephonic communication thereover. Eachof the conductors at and 5 provides a telegraph channel over which telegraphic impulses may be transmitted in but one direction at a time. To the terminal ends of the line conductors, transmitting and receiving mechanisms are connected. As shown in Fig. 1, with the line conductor 4, there is associated a transmitting key 8 which, when operated, causes the energization of a pole changer relay 7 which in turn controls the application to the line ofv current impulses of both negative and positive polarity. F or smoothing out the impulses, or, in other words, eliminating certain objectionable harmonics produced due to such reversals of polarity by the relay 7, an inductance 10 is connected in series with the line conductor 4, which is grounded at one terminal of the inductance through a condenser 9 and a resistance 11. The provision of such a combination provides what is commonly known asa noise killer for filtering out certainobjectionable harmonics produced due to the operation of the transmitting equipment of the telegraph set.

Like other well-known telegraph systems the receiving equipment comprises a receiv-v mission of telegraphic and telephonic messages, condensers and inductances forming the composite set are'connected in bridge of the line conductors 4 and 5, as shown in the dotted rectangle and to which the usual composite ringer is connected. The conductors connected with the bridge "circuit terminate in a ack 14:. The telephone (not shown) is connected to the respective conductors of a plug 15 designed to cooperate with the contacts of the jack 14, making it possible to connect the telephone with the line conductors 4 and 5. I

During the period of operation of the transmitting equipment of the telegraph apparatus,linterfering currents traverse the condensers and inductances forming a part of the composite setto the conductor 5 and thus leak off through the winding of the receiving relay 12. The current passing through the winding of the receiving relay 12 in this manner often times is of suflicient strength to cause the relay 12 to respond, thus causing the false operation ot' the receiving sounder 13. The present invention, however, obviates the false operation of the receiving relay 12 by the connection of a leakage path extending from the line conductor 4: to one winding of the receiving relay 12. This leakage path comprises inductance 17, a condenser 19 and a resistance 20, the mid-point of the inductance 17 being grounded through a condenser 18. The values of the respective units forming the leakage path just mentioned, are such as to produce a current wave which will be of the same amplitude phase relation and wave shape as the current wave which is impressed on the line conductor 5, through the composite set shown in the rectangle. By having the mid points oi the inductance l7 grounded through acondenser, a current wave, which more nearly simulates the one impressed on the conductor through the composite set will be applied to the winding of relay 12, than it the condenser we're positioned at a diii erent point with respect to the induction coil 17. It is thus apparent that by the impression on one winding of the receiving relay 12, of an impulse which is of the same amplitude, phase relation, and wave shape as that impressed on the line conductor through the composite set, the ctfect of such impulses may be neutralized by opposing their magnetic eiiects in the relay 12, thus preventing the false operation of the receiving relay 12.

When the telephone is connected, or in other words, the plug 15 inserted in the jack 1 1, the impedance of the circuit is niaterially changed, thus making it, in general, necessary to increase the current flowing through the leakage path extending from the conductor 4 to one win-ding of the receiving relay 12. This is accomplished by the addition of a contact to the jack 1 1-, which is closed upon the insertion of the plug 15. When the contact 16 is closed a portion of the resistance 20 is short-cirtaiited.

In Fig. 2, 25 and 26 represent two telegraph signaling circuits, which have associated therewith the terminal circuits and B, respectively, and which have connected in bridge thereof, the composite set, as shown in the dotted rectangle, for permitting the simultaneous transmission of telegraphic and telephonic currents. The ends of the conductors 25v and 26 terminate in thewindings of the bridged coils 27, 28 and 29,, 30, respectively, thereby permitting duplex service. Across the outer terminals of these coils are connected the polar relays 31 and 32, which control the energization of re ceiving sounders 33 and 34:, respectively. Connected to the windings28 and 29 cf the respective ratio arms, are the artificial balancing networks AL and AL,, which serve to balance the real line conductors 25 and 26, respectively, as is well known to those skilled in the art.

The terminal circuits A and B also coinprise transmitting keys 35 and 36, which serve to directly apply to the apex of the respective ratio arms impulses of opposite polarity or may, as shown in Fig. 1, control the operation of a pole-changer relay 7, which, in turn, causes the impression on the line conductor, of an impulse, the polarity of which corresponds to the operation of the respective key.

For neutralizing the effect of the current which is impressed on the line conductor 26 fronr the line conductor 25, through the composite equipment, and vice versa, leakage path is provided extending from the apex or each ratio arm to a winding of the ratio aim associated with the other conductor. This leakage path comprises a resistance 38, an inductance 39, the mid-point of which is grounded through the condenser iii), a condenser 41, and an inductance coil i2, which is positioned in inductive relation with the winding 29. A similar leak path is provided from the common junction of coils 29 and 30. It is thus apparent that upon each operation of the telegraph key 35, a current will be impressec onthe winding 29, which is in a direction opposite to the current impressed on the line conductor 26 through the composite set, thereby neutralizing the effect of the current impressed on therelay 32 through the compositesct, and by so selecting" the values of the units forming the leakage pathjust described, the amplitude,'ph'ase relation and the waveshape ot the current impressed on the winding 29 through the coil 412 maybe socontrolled as to entirely offset the effectof any current which may be impressed on the line conductor 26 through the composite set. When the telephone is connected as in the previous case, a poztiono'fi the. resistance is slmrt-circuited.

, Conditions similar to those just described are produced upon the operation or" the telegraph key 36 for neutralizing the effects oi current impulses which may be impressed on the line conductor 25 t'lom the line conductor 26, through the composite set, thereby preventing-the false operation of the receiving relay 3].

Although the invention has been applied in a. specific manner, it is, of course, obvious that many departures may be made within the scope of the present invention.

lVhat is claimed is:

1. In a signaling system, a composite telephone and telegraph system,"a'1'netallic line circuit joining two stations, telegraphic receiving and transmitting apparatus individual to each side of said line circuit, a composite set coimected with said line circuit at a point intermediate the telegraph apparatus and the line circuit and means for impressing on one of the conductors formlng said metallic line circuit an impulse of a character adapted to neutralize the current produced therein through the composite set by the transmission of signaling impulses over the other conductor of said metallic line circuit.

2. In a signaling system, a composite tele phone and telegraph system, a pair of line conductors joining two stations, a composite set in bridge of said conductors, duplex tele graph equipment associated with each 01 said conductors having telegraphic receiving and transmitting apparatus individual thereto, and means for impressing on the respective conductors an impulse of a character adapted to neutralize the current produced'therein through the composite set by the transmission of telegraphic impulses over the other of said conductors.

3. In a signaling system, a composite telephone and telegraph system, a pair of line conductors joining two stations, a composite set in bridge of said conductors, a pair of ratio arms associated with each conductor,

transmitting and receiving telegraph ap paratus associated with said ratio arms, and a leakage path operatively associated with the apex of the ratio arms on one conductor and one of the ratio arms on the other conductor and comprising a resistance, a condenser, and an inductance whereby an impulse is impressed on each conductor of a character adapted to neutralize the current produced therein through the composite set by the transmission of telegraphic impulses over the other conductor.

4. In a signaling system, a composite telephone and telegraph system, a pair of line conductors joining two stations, a composite set in bridge of said conductors, a pair of ratio arms associated with each conductor, transmitting and receiving telegraphic apparatus connected to said ratio arms, and a leakage path operatively associated with the apex of the ratio arms on one conductor and one of the ratio arms on the other conductor consisting of an inductance, the mid-point of which is grounded through a condenser whereby an impulse of a character adapted to neutralize the current produced in each conductor through the composite set by the transmission of telegraphic impulses is impressed in the other of said conductors;

5. In a signaling system, a composite telephone and telegraph system, a pair of line inductively connected with the ratio arms on the oti er conductor whereby upon the op eration of the transmitting equipment, an impulse will be impressed on each ratio arm to neutralize the current produced by interfering currents induced therein due to the cross-fire produced through the composite set.

6. In a signaling system, a plurality of conductors, means for impressing signaling currents of one type on each of said conductors, coupling means between said conductors, means for impressing on said conductors through said coupling means signals of a difi'erent type, means for preventing said coupling means from causing currents to be developed in one of said conductors due to said signaling currents in another of said conductors, and means for changing the characteristic of said preventing means when signals of a different type are impressed on said conductors due to the operation of said third recited means.

i 7. A composite signaling system comprising a plurality of line conductors, a. composite set bridged across said conductors, and means for impressing on one conductor currents that will substantially neutralize currents produced in said one conduct-or through the intermediary of said composite set due to signaling currents in another of said conductors.

8. A composite signaling system comprising a plurality of line conductors, a composite set bridged across said conductors, and means for impressing on one conductor currents that will substantially neutralize currents produced in said one conductor through the intermediary of said composite set due to signaling currents in another of said conductors, said means comprising a resistance, inductive and capacitive reactances of such values that the neutralizing current has the samev wave form, phase relation and amplitude as the wave form to be neutralized.

In witness whereof, I hereunto subscribe my name this 11th day of March, A. D., 1922.

GEORGE O. CUMMINGS. 

